: Intermittant detonation

08-07-05, 08:37 AM
On my recently aquired 96 Deville, I experience heavy detonation episodes during intermittant heavy throttle applications. This detonation occurs on one out of every ten heavy throtle applications. It does not matter if it is a WOT or one half of a WOT. It is so unnerving that my reaction it to take my foot right out of it. One one occasion the detonation continued into the subsequent up shift.
I suspect a defective knock sensor. There are no current codes. I do get a Service transmission display on the DIC with the related service engine soon light. I am running 93 octane.
Has anyone ever experienced anything like this?


08-07-05, 10:05 AM
Anything showing up from the OBD II? Post some codes or check them at:


08-07-05, 10:56 AM
As Eldfig said, check for DTC's first. I would guess knock sensor or EGR but either should set a DTC I think. EGR will be easy to clean but hard to remove if you've had the fuel rail recall done.

08-09-05, 12:12 PM
There are two codes that are coming up on the DIC PC0603 and PC0717. Both are history. No current codes come up.
From my 4.9 experience, an EGR problem is noted for light detonation during medium engine loads. My issue is a violent detonation that does not occur every time heavy throttle is applied, but perhaps 1 in every 10 heavy throttle applications.
I will be cleaning the EGR passages as well as inspecting the two crank position sensors. I also plan on pulling codes with a scanner to see if there is any other codes present that the DIC does not detect.
Any other suggestions